The invention relates to a rock drill for rotary and/or percussion stress, in particular for percussion or hammer drilling machines.
The production of feed spirals on rock drills usually takes place by milling or whirling. Special forging processes for the production of the drill have also become known. In the case of all processes, the single or double thread feed spiral runs uniformly around the drill shank to the drill head, the spiral pitch being variable, if appropriate, over the length of the feed spiral.
It has become known from German Patent Specification 2,013,327 to design the feed spiral not smooth but staircase-shaped in order to prevent the drilling dust present in the feed spiral slipping due to feed sections with a slight pitch on the feed spiral. In this case, during percussion drilling, the combined rotary and axial movement of the drilling tool is utilised, the drilling tool spinning underneath the drilling dust after axial movement and the associated raising of the said dust, and the raised particles dropping onto the next higher staircase section. The intention of this is to achieve an improved feed without a tendency to clog, it being possible to increase the pitch angle and thus the feed rate.